Enhancement of effective electromechanical coupling factor by mass loading in layered SAW device structures

Abstract

This paper describes drastic enhancement of K_e² by mass loading in layered SAW device structures such as the ScAlN film/Si substrate. It is shown that this phenomenon is obvious even when an amorphous SiO₂ film is deposited on the top surface for temperature compensation. This enhancement is caused by SAW energy confinement to the top surface of the ScAlN layer where the IDT is placed. This K_e² enhancement is also found when other electrode and/or substrate materials are employed.